1. Field of the Invention
This invention relates to the design of large electrodynamic equipment, such as electrical generators. More specifically, this invention relates to an improved cooling system for the end turn region of a strap-wound rotor coil in an air-cooled electrical generator.
2. Description of the Prior Art
Economic concerns dictate that large, air-cooled electrical generators of the type that are manufactured by the assignee of this invention, Westinghouse Electric Company, be designed to as high a power density as possible, as well as being simple to manufacture.
The higher the power density of an electrical generator, the more heat that is produced in the stator and rotor windings during normal operation. The need to conduct waste heat away from the stator and rotor windings thus operates as a significant constraint to the power density that can be achieved.
Traditionally, the end turn region of strap-wound rotor windings have been difficult to effectively cool. One method of cooling the end turns involves machining ventilation channels into fiberglass blocking that is located between the coil end turns, thus conducting heat away from the side surfaces of the coils. However, the effectiveness of such ventilation channels is limited, and is inadequate to provide the cooling that would is necessary at the level of power densities that the designers of such equipment are trying to achieve.
It is clear that there is a long and unfilled need in the prior art for an improved method and system for cooling the end turn regions of strap-wound rotor coils in an electrical generator.